Dimdim Castle (Kurdish: قەڵای دمدم, romanized: Qelay Dimdim, Persian: قلعه دمدم) was a Kurdish fortress located on top of Mount Dimdim in West Azerbaijan Province of Iran, just west of Lake Urmia. This fortress was the location of the Battle of Dimdim.

According to Kurdish oral tradition the fortress was built in the pre-Islamic era. The castle suffered an attack by the Safavid Empire and was sacked in 1609, then rebuilt by the Amir Khan Lepzerin in the same year. Other source mentioned that the siege of Dimdim Castle was in 1610.

The word "Dimdim" may be onomatopoeic for the noise which the stones of the castle made when they dropped from the castle into the valley.